Recipes that create basic materials like leather, coarse bone powder etc. are worth keeping to sell, as well as recipes for soul shots and blessed spiritshots.
All basic materials are worth keeping, all materials that are used to make specific items are probably not worth keeping for a long itme.
If I could, I would say all generic mats. The recipes, etc at the lower levels are everywhere, so those I would sell off to the store.
I also kept my squire's stuff on the last toon I made just to have it. I wish I would have done that on the other ones now looking back.
Your problem is the size of your warehouse. Once you get above 40, alot of the other stuff just takes up room.
Oh, one more thing I keep is all Chronicle Update Items.
Yep Mr Eastwood, keep all basic mats, you're going to need 'em later on, basic mats recipes and shots recipes are keepers too if you have the patience to put 'em in your sell store for other players. I dont know what goes around on your server for compressed shotpackage recipes though, myself i never found a need for them nor managed to sell 'em to other players so i just gave it all to NPC shops.
Keymats for both weapons and armors you can sell top a regular NPC shop all the way up to B grade stuffs (unless you see a buyshop around somewhere else... i know brig helm designs are easy to get a good price for on Hinde and thats a D grade item) thats when you can start saving it and selling to other players or keep for your own crafting purposes